A patient monitoring/defibrillation instrument displays patient vital signs in numeric form or as graphical waveform traces. Under normal room lighting conditions the numeric and waveform information is displayed in color against a black or gray background. When the patient monitor is operated outside or in bright light, the user has the option to select a color map for display of the patient vital signs information in a highly contrasting manner such as black numeric or waveform information against a bright background such as yellow. The high contrast display, while being objectionable in most indoor settings, has been found to comfortably and effectively display the monitored information in sunlight without the need to increase power to the display.